Solar Panel Orientation, Tilt, and Shading: How Much They Actually Matter

Roof orientation and shading are the two site-specific factors that matter most for how much a given system actually produces — more than panel brand in most cases.

Orientation: south is best, but not required

In the Northern Hemisphere, a true south-facing roof captures the most total sunlight over a day and year, and is the benchmark installers compare other orientations against. East or west-facing roofs typically produce roughly 15-20% less than an equivalent south-facing array, but are still very much worth installing on — many homes successfully split panels across east and west-facing roof planes for a flatter production curve across the day (more morning and evening output, less midday peak) rather than a lower total.

North-facing is the one to be cautious about

A purely north-facing roof in the Northern Hemisphere sees meaningfully reduced production — often 30%+ less than south-facing — and is generally the least favorable orientation, though not automatically disqualifying if it's your only option and you're comfortable with the reduced output.

Tilt angle

The theoretical optimal tilt roughly matches your latitude, but real-world roofs rarely allow fine-tuning, and the production difference between a "good enough" tilt (typically 15-40 degrees for most U.S. latitudes) and a perfectly optimized one is usually a few percentage points — not worth re-engineering your roof over.

Shading is the bigger production killer

A single tree or chimney shadow crossing part of an array during peak sun hours can cost far more production than a suboptimal orientation or tilt — and with older string-inverter systems, shading on even one panel can drag down the output of the entire connected string. Microinverters or power optimizers largely solve this by letting each panel perform independently, which is why installers often recommend them specifically for roofs with partial shading.

Getting a real answer for your roof

Ask your installer for a shading analysis specific to your address — most use satellite or on-site tools (like a Solar Pathfinder or drone-based LIDAR scan) that model shadow patterns across the full year, not just a snapshot on the day they visit. This is a far more reliable answer than a generic "south-facing is best" rule applied to your specific roof.